This application is based on and incorporates herein by reference Japanese Patent Application No. 2000-317812 filed on Oct. 18, 2000.
1. Field of the Invention
The present invention relates to an apparatus to control an amount of fuel supply to an internal combustion engine.
2. Description of Related Art
Conventionally, a technique to determine the properties of fuel based on variations in rotation speed Ne upon or immediately after startup of internal combustion engine is known.
However, there is no technique to estimate an air-fuel ratio (hereinafter referred to xe2x80x9cA/Fxe2x80x9d) from the variation amount of the rotation speed Ne instead of the determination of fuel properties.
An object of the present invention is to provide an internal combustion engine fuel supply amount control apparatus to estimate an A/F based on the rotation speed Ne of the engine and accurately control the air-fuel ratio immediately after startup of the engine based on the estimated A/F.
According to the present invention in the internal combustion engine fuel supply amount control apparatus in claim 1, an air-fuel ratio of an internal combustion engine during a predetermined period is estimated based on a load on the internal combustion engine detected by load detection means. In this constitution, as the air-fuel ratio can be estimated in correspondence with the load on the internal combustion engine, control based on the air-fuel ratio can be performed even before an A/F sensor is activated. Especially, optimum combustion can be performed from the startup of the internal combustion engine. Note that the xe2x80x9cloadxe2x80x9d here may be a general load such as an intake air amount, an intake pipe pressure and an intake air flow speed, but may more preferably be a rotation speed of the internal combustion engine.